1. Technical Field
The present invention relates to the carrying of data storage discs in a precise disposition. In particular the invention relates to the manufacturing process for such discs wherein blank discs are provided with tracks and other basic structure.
2. Related Art
The data storage discs used in the invention may have data written in either magnetically or optically such as by laser beam, and include hard and floppy magnetic discs and CD Roms.
In general there is a desire to provide ever increasing data storage densities on storage discs. This is particularly important in the case of hard disc drives as used for example in PCs and laptop or notebook computers. More storage is required but the physical size of the hard drive needs to be minimized. In recent times such increased storage densities have been achieved largely by writing an ever increasing number of tracks onto the storage discs during manufacture. This means that if there are not to be track errors, the storage discs must be mounted extremely precisely. In some cases, the mounting needs to be to a greater precision than that to which internal bores of the discs themselves are produced. Further, for various reasons, the speed at which the discs are rotated during track writing cannot be increased indefinitely. This means that an increased number of tracks leads to an increased processing time. Thus it becomes particularly desirable to be able to write the tracks onto a number of discs simultaneously. Moreover it is desirable if it is possible to write the tracks of the discs before they are assembled into a stack in the final disc drive.
In these and other circumstances it can be desirable to be able to mount a stack of the discs in a manner which allows for precision rotation and writing to and reading from each disc, and which preferably allows subsequent releasing of the discs.
In such a case, the discs should be mounted as a stack so that each disc locates on a hub with accuracy and should be accurately centered with reference to a main axis of rotation. Moreover, there should be a space in the axial direction between each disc to permit reading and writing data on the disc.